Pragyaan rover has been travelling on the lunar surface since its deployment from the Vikram lander of the Chandrayaan-3 mission. India’s Chandrayaan-3 space probe touched down at the moon’s south pole last week. The rover has so far covered a distance of about eight metres and has sent back regular updates on its progress, including photos of its surroundings and details about the obstacles it has encountered.

The Pragyaan rover is equipped with a variety of scientific instruments, including a spectrometer, a camera, and a magnetometer. These instruments will be used to study the lunar surface, including its composition, mineralogy, and geology. The rover will also search for signs of water ice, which could be a valuable resource for future human missions to the Moon.

The Pragyaan rover is expected to operate for about 14 days on the lunar surface. During this time, it will conduct a variety of experiments and collect data that will help scientists better understand the Moon.

The rover’s progress is being closely monitored by scientists and engineers at the Indian Space Research Organisation (ISRO).

Before its disembarkation, the Vikram lander captured videos and images of the Pragyaan rover, showcasing its appearance and readiness for its lunar adventure. The Pragyaan rover directed its camera towards the Vikram lander and playfully quipped, “Smile, please!” The black-and-white image captured the Vikram lander with all four legs planted on the lunar surface. The image was captured using the rover’s navigation camera.

The rover’s laser detector conducted “first-ever in-situ measurements” of the elemental composition of the lunar surface in the vicinity of the south pole. The measurements revealed the presence of various chemicals, including sulphur and oxygen, in the lunar soil.

Preliminary analysis also revealed the presence of other elements—aluminium, calcium, iron, chromium, titanium, manganese, silicon, and oxygen. The detection of sulphur offers insights into the Moon’s volcanic history and its intricate relationship with the broader solar system.

Noah Petro, a project scientist at NASA, acknowledged that the presence of sulphur in lunar soil has been documented since the 1970s, thanks to samples obtained from the Apollo and Luna missions. However, he emphasised that the Pragyaan rover’s measurements mark an extraordinary achievement in lunar research.

Sulphur is considered a volatile element unless it is encapsulated within a mineral structure. Petro explained that if sulphur exists on the lunar surface without being part of a crystal or mineral, its presence becomes a notable observation in its own right.

Petro further praised the ISRO for its feat of directly measuring sulphur on the lunar surface using the rover.

Two days after landing, ISRO reported that Pragyaan, with its steady pace of one centimetre per second, had successfully travelled a remarkable distance of eight metres (26 feet).

However, the deep craters that punctuate the lunar landscape posed potential hazards and required Pragyaan to make strategic adjustments to its path for safety.

Pragyaan came across one such crater with a diameter of four metres. The rover’s advanced detection capabilities allowed it to identify the crater when it was approximately three metres away from it. Responding swiftly, ISRO issued commands for the rover to backtrack along its path, ensuring its safety by navigating away from the potential hazard.

ISRO also announced temperature data gleaned from the Moon’s surface. The initial dataset sheds light on the thermal characteristics of the lunar environment.

The dataset encompasses temperature readings that span the lunar topsoil and penetrate up to 10 centimetres beneath the surface. The measurements were gathered using the ChaSTE experiment—Chandra’s Surface Thermophysical Experiment—situated aboard the Vikram lander.

The ChaSTE experiment is equipped with a suite of 10 individual temperature sensors. This ensemble of sensors enabled ISRO to capture and analyse temperature variations at an unprecedented level of detail.

Surface temperatures, as revealed by the ChaSTE experiment, hovered around 60°C (140°F), attesting to the Sun’s impact on the lunar surface. However, the temperature narrative shifted as the probe delved beneath the surface. At an approximate depth of 80mm (3 inches), the temperature experienced a plunge, plummeting to -10°C (14°F).

ISRO scientist BH Darukesha expressed his surprise at the significant temperature fluctuations. The initial anticipation was for surface temperatures to hover around 20-30°C (68-86°F). However, the actual temperature readings, reaching up to 60°C (140°F), surpassed these expectations, illuminating the complexities that govern the Moon’s thermal dynamics.

The Moon’s poles are home to even more extreme conditions. One example is a crater near the north pole that recorded a temperature of -410°F (-250°C), making it the coldest temperature ever registered across the entire solar system. Similar icy conditions have been documented in craters near the lunar south pole that remain perpetually shadowed by sunlight.